Low frequency acoustic projectors for underwater acoustic applications can be expensive due to their generally complex designs and components. One type of low frequency acoustic projector is a moving coil type low frequency projector. Underwater acoustic moving coil type low frequency projectors are generally large, expensive, and include complex designs. The complex designs are at least partially a result of the moving coil apparatus being sensitive to pressure differentials between an internal cavity side of a projector face and an external side of the projector face that is in communication with the water. Moving coil type low frequency acoustic projectors can be de-tuned (e.g., frequency modified) if the forces acting on the projector face are not maintained in static equilibrium. To maintain static equilibrium, pressure is often supplied to the internal cavity, which can limit depth of operation and increase the size and complexity of the design, and accordingly, increase the expense as well. Known methods of supplying pressure to the internal cavity include using a self-contained underwater breathing apparatus (SCUBA) system, an air-backed system, or an oil-compensated system.